X-tians are often desperate to link atheism to the horrors of Nazi Germany. You can see this expressed in the conclusion of Ben Stein's Expelled. A google search for "atheism" and "nazi" produces the headline "Hitler was an Atheist Who Killed Millions in the Name of Atheism".
While it is largely a moot point what exactly was Hilter's religion, we can say what informed the antisemitism of the Nazi Party and German Society at Large with absolute certainty. Christianity has a long and recorded history of promoting hate for the Jewish people. One of the superstars of Christian antisemitism is none other than Martin Luther of the Reformation (a German). As mentioned before in this blog Luther authored many hateful pieces of literature, such at ones with winning titles like "The Jews and Their Lies".
It would be this historical christian brand of antisemitism that would inform and reinforce The Nazi Party and German society's view of their Jewish neighbors. We can see examples of this from contemporary German X-tian leaders. Check out
this article about the Kristallnacht from Wikipedia:
Bishop Martin Sasse, a leading Protestant churchman, published a compendium of Martin Luther's writings shortly after the Kristallnacht; Sasse "applauded the burning of the synagogues" and the coincidence of the day, writing in
the introduction, "On November 10, 1938, on Luther's birthday, the synagogues are burning in Germany." The German people, he urged, ought to heed these words "of the greatest anti-Semite of his time, the warner of his people against the Jews. "Diarmaid MacCulloch argued that Luther's 1543 pamphlet On the Jews and Their Lies was a "blueprint" for the Kristallnacht.
The Kristallnacht (or Night of the Broken Glass) were two nights of anti-Jewish rioting that was encouraged by the Nazi Party. While there were more secular support for the riots and the regime in general, I have no doubt that it was historical and X-tian brand of antisemitism that made the Regimes violence towards Jewish and moderates easier to swallow.